There are numerous fields in which heat is used to transform a characteristic of a material. The application of heat to certain materials, for example plastic resins, increases the plasticity thereof. The controlled application of heat to certain steels, however, can have the opposite effect, increasing the hardness (R.sub.c) of the metal.
There are several problems associated with heat treating materials. These problems are often complementary, contradictory, or both. It is necessary at times to provide sufficient heat to transform the desired characteristic of a material while avoiding the application of too much heat. It may be desired, for example, to heat a material enough to make the material plastically deformable without actually melting the material. The amount of heat must be carefully controlled.
The directionality of the heat being used also presents problems. It is sometimes necessary, for example, to treat only a portion or a surface of a body. One current method of achieving this is simply to heat the entire body. This method wastes the majority of the heat generated, costing money and expending resources. Moreover, it is often desired that different portions of the body have different characteristics. Heating the entire body in order to heat only a portion would destroy these differences.
The use of more directionally controllable heating devices, such as gas jets or lasers, also has problems. While these devices can be fairly precisely aimed, the total area being heated at a given time is small. Thus, where an entire surface is to be heated, these devices cannot maintain a steady, even heat over the whole surface.
Another problem with radiant heaters or gas jets is the relatively long amount of time needed to achieve a desired temperature. A primary problem is the cost of the energy being consumed during the heating time. A secondary problem is simply the consumption of time. Moreover, if one of these methods is being used to treat only a portion of a body or surface, the longer time permits the remaining portion to at least approach the final temperature, either through conduction from the portion of interest or directly by the heating means.
Current methods of heating only a portion of a material or body, or of achieving a temperature in only a discrete layer of an object, are wasteful of energy, slow, and inefficient. There is thus room for improvement in the art.